Selection in pigs for increased lean growth rate on a time-based feeding scale

1988 ◽  
Vol 47 (1) ◽  
pp. 149-156 ◽  
Author(s):  
C. P. McPhee ◽  
G. A. Rathmell ◽  
L. J. Daniels ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Variance Components ◽  
Performance Test ◽  
Selection Criterion ◽  
Live Weight ◽  
Control Line ◽  
Lean Tissue ◽  
Lean Growth ◽  
Ad Libitum ◽  
And Control

AbstractSelection was carried out in a line of pigs for increased growth rate of lean tissue. The selection criterion was weight of lean in the ham predicted from live backfat and weight measurements after a 12-week performance test commencing at 25 kg live weight. All pigs were given the same total amount of food over the test period. The scale was set to about proportionately 0·85 of predicted ad libitum intake. Boars selected with an intensity of 1/12 were used for 6 months and sows selected with an intensity of 1/4 were kept for two farrowings. An unselected control line was maintained concurrently.After five generations, performances of selected and control line pigs were compared on ad libitum and scale feeding as they grew to 85 kg. Responses in the selected line on scale feeding were +51 g/day for growth rate (GR), −0·16 for food conversion ratio (FCR), −2·2 mm for backfat (F) and +0·47 kg for ham lean (HL). On ad libitum feeding, responses were much higher in the selected line, giving rise to line × food interactions. Responses were +128 g/day for GR, −0·27 for FCR, −2·3 mm for F, +1·01 kg for HL and +0·15 kg/day for food intake (FI). Estimates of the heritability of HL from variance components were 0·43 (s.e. 0·15) on scale feeding and 0·28 (s.e. 0·19) on ad libitum feeding. The realized heritability of HL on scale feeding was 0·29 (s.e. 0·04) and its co-heritabilities with the other traits on both feeding levels were of similar magnitude to its heritability. Scale feeding exposed genetic variation in the partitioning of food between lean and fat deposition and appeared to be a suitable selection regimen for performance on ad libitum feeding.

The consequences of index selection on carcass composition in Suffolk sheep

1999 ◽  
Vol 1999 ◽  
pp. 46-46 ◽  
Author(s):  
R. M. Lewis ◽  
G. C. Emmans ◽  
G. Simm ◽  
W. S. Dingwall ◽  
J. FitzSimons ◽  
...  
Keyword(s):  
Performance Test ◽  
Selection Index ◽  
Live Weight ◽  
Growth Index ◽  
Carcass Composition ◽  
Control Line ◽  
Lean Growth ◽  
Selection Decisions ◽  
Terminal Sire ◽  
And Control

Early in the 1980s a selection index was designed at SAC to improve the rate of lean growth in terminal sire sheep which combined ultrasound measurements of fat and muscle depth, and live weight at 150 days of age (Simm and Dingwall, 1989). Beginning in 1985, this index was applied in the SAC Suffolk flock in a performance test. In 1994, rams from a line selected on this index weighed on average 12% more (8 kg) and had 12% lower fat depth (– 0.9 mm) and 10% higher muscle depth (2.9 mm) than rams from an unselected Control line. Comparison of Selection and Control line animals has thus far been based on live predictors of carcass composition at weights substantially heavier than typical market lamb weights. The aims of this study were to test whether selection decisions based on the lean growth index produced an improvement in actual carcass composition in purebred terminal sire sheep and whether these changes persisted at live weights different from those under which selection was carried out.

Selection for components of efficient lean growth rate in pigs 2. Selection pressure applied and direct responses in a Landrace herd

1994 ◽  
Vol 59 (2) ◽  
pp. 263-269 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran
Keyword(s):  
Growth Rate ◽  
Genetic Correlations ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Direct Response ◽  
Lean Growth ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

AbstractResponses to divergent selection for lean growth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Landrace pigs were studied. Selection was practised for four generations with a generation interval ofl year. A total of 2642 pigs were performance tested in the high, low and control lines, with an average of 37 boars and 39 gilts performance tested per selection line in each generation. The average within-line inbreeding coefficient at generation four was equal to 0·04. There was one control line for the DFI and LFC selection groups and another control line for the LGA selection group. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively with ad-libitum feeding. The selection criteria had phenotypic s.d. of 32, 29 and 274 units, for LGA, LFC and DFI, respectively, and results are presented in phenotypic s.d.Cumulative selection differentials (CSD) were 5·1, 4·5 and 5·5 phenotypic s.d. for LGA, LFC and DFI, respectively. Direct responses to selection were 1·4,1·1 and 0·9 (s.e. 0·20) for LGA, LFC and DFI. In each of the three selection groups, the CSD and direct responses to selection were symmetric about the control lines. The correlated response in LFC (1·1, s.e. 0·19) with selection on LGA was equal to the direct response in LFC. In contrast, the direct response in LGA was greater than the correlated response (0·7, s.e. 0·18) with selection on LFC. There was a negative correlated response in DFI (-0·6, s.e. 0·18) with selection on LFC, but the response with selection on LGA was not significant (0·2, s.e. 0·16).Heritabilities for LGA, LFC and DFI ivere 0·25, 0·25 and 0·18 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·12 (s.e. 0·02). Genetic correlations for LFC with LGA and DFI were respectively positive (0·87, s.e. 0·02) and negative (-0·36, s.e. 0·09), while the genetic correlation between DFI and LGA was not statistically different from zero, 0·13 (s.e. 0·10). Selection on components of efficient lean growth has identified LGA as an effective selection objective for improving both LGA and LFC, without a reduction in DFI.

Effects of crossbred ewe genotype and ram genotype on ewe prolificacy, lamb viability and lamb output in the lowland sector

2002 ◽  
Vol 139 (2) ◽  
pp. 169-181 ◽  
Author(s):  
L. E. R. DAWSON ◽  
A. F. CARSON
Keyword(s):  
Growth Rate ◽  
Northern Ireland ◽  
Growth Rates ◽  
Genetic Improvement ◽  
Live Weight ◽  
Growth Index ◽  
The Other ◽  
Lean Growth ◽  
And Control ◽  
Lamb Growth

A study was carried out on five lowland farms in Northern Ireland over 3 years to investigate the effect of crossbred ewe and ram genotype on ewe prolificacy, lamb viability and weaned lamb output. Four crossbred ewe genotypes were sourced from six hill farms involved in a previous study – Bluefaced Leicester×Blackface (BLXB), Texel×Blackface (TXB), Suffolk×Cheviot (SXCH) and Texel×Cheviot (TXCH). On each farm, groups of 20–30 of each crossbred ewe genotype were mated with Suffolk or Texel rams. Throughout the 3 years of the study, the ewe genotypes lambed at 1, 2 and 3 years of age. Within each of the ram breeds, high lean growth index rams sourced from UK sire reference schemes were compared with rams sourced from flocks not involved in objective genetic improvement programmes (control). BLXB ewes were the most prolific of the four ewe genotypes producing 1.73 lambs per ewe lambed compared with 1.47 for TXB, 1.46 for SXCH and 1.41 for TXCH (P<0.001). Lamb mortality was similar for the four ewe genotypes, thus number of lambs weaned was greatest for the BLXB ewes (P<0.001) with the other three crosses producing similar numbers of lambs. A greater proportion (P<0.05) of SXCH ewes lambed without assistance compared with BLXB and TXB ewes and a greater proportion of TXCH ewes had abundant supplies of colostrum compared with the other crosses (P<0.10). Output of weaned lamb per ewe lambed and per ewe metabolic live weight (P<0.001) was greatest in the BLXB ewes. Ewe productivity, prolificacy, number of lambs weaned and the proportion of ewes lambing without assistance increased with ewe age (P<0.001). Lamb growth rate from birth to 6 weeks and from birth to weaning increased with ewe age (P<0.05). Crossbred ewes lambing at 3 years old had a greater output of weaned lamb compared with ewes lambing at 1 and 2 years old (P<0.001). Ram genotype had no effect on ewe prolificacy, lamb viability or pre-weaning growth rates, although Texel-sired lambs had lower birth weights than Suffolk-sired lambs and control-sired lambs had lower birth weights than high lean index-sired lambs (P<0.05).

LIVE PERFORMANCE AND CARCASS CHARACTERISTICS OF BEEF BULLS IN RELATION TO SELECTION FOR YEARLING WEIGHT

1970 ◽  
Vol 50 (3) ◽  
pp. 491-497 ◽  
Author(s):  
A. H. MARTIN ◽  
H. T. FREDEEN ◽  
J. A. NEWMAN
Keyword(s):  
Growth Rate ◽  
Live Weight ◽  
Direct Selection ◽  
Control Line ◽  
Live Performance ◽  
Carcass Yield ◽  
Yield And Quality ◽  
Lean Growth ◽  
Kidney Fat ◽  
Selection For

Data over two years on a total of 149 Shorthorn bulls from a closed herd under direct selection for yearling weight were used to examine line differences in carcass yield and quality and to evaluate relationships between live performance and carcass yield and quality. No significant differences [Formula: see text] in performance or carcass data between control and selected lines were apparent in 1967. However, in 1968 bulls from the selected line were heavier at slaughter (470.5 kg vs. 441.8 kg), their carcasses contained more kidney fat (9.14 kg vs. 8.46 kg), and they had larger loin eye area but smaller weight-adjusted loin eye area. Rate of gain was superior for the selected line whether examined as live-weight, carcass weight, trimmed primal cut weight or lean weight per day of age. There were no significant differences between lines for percent fat, lean or bone in primal cuts, or for rib fat thickness, percent trimmed prime cuts, percent seam fat, muscle/bone and hind/front ratios, or for chemical composition or tenderness evaluations of the longissimus dorsi. Averaged over the two years and at the same averaged slaughter weights (418 days), selected-line bulls produced a significantly greater quantity of total carcass, of trimmed primal cuts and of total lean than did the control-line bulls; selection for yearling weight appeared to have been effective in increasing rate of lean growth. Phenotypic correlations indicated that liveweight/day of age was more highly related to variation in lean growth rate than growth rate of fat. From 20 to 60% of the variation in wholesale cut weights was associated with differences in rate of gain. Distribution of the gains was little influenced by rate of gain. Tenderness evaluations were not related to live performance.

Responses in gilt traits measured during performance test, at mating and at farrowing with selection for components of efficient lean growth rate

1996 ◽  
Vol 63 (2) ◽  
pp. 235-241 ◽  
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Performance Test ◽  
Growth Traits ◽  
Live Weight ◽  
Selection Strategy ◽  
Mating Period ◽  
Lean Growth ◽  
Daily Food ◽  
Reproduction Traits ◽  
Selection For

AbstractThe responses in traits measured at the start of the mating period and at farrowing were examined after seven generations of divergent selection for daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-\ibitum feeding and lean growth on scale feeding (LGS). Weight and backfat depth at mating were measured on 330 gilts and 74 boars, which were selected on the basis of performance test traits. Farrowing information was available on 259 gilts. At the start of the mating period, gilts selected for high DFI, LGA or LGS had similar live weights (135, 137 and 137 (s.e.d. 4·5) kg) but different backfat depths (20·3, 14·0 and 11·3 (s.e.d. 1·3) mm) while the corresponding low lines had different live weights (129, 117 and 124 kg), but similar backfat depths (17·5, 17·8 and 17·8 mm). Gilts selected for high LFC had lower mean live weight and backfat depth (114 kg and 10·7 mm) than gilts in the other selection lines. Conception rates of gilts selected for low DFI or high LGS were similar (0·62 and 0·64, s.e.d. 0·12) and lower than for the alternative selection strategies (0-78), but the low DFI gilts were significantly older at farrowing than gilts selected for high LGS (424 v. 408 (s.e.d. 5·5) days). Responses in live weight, backfat depth, age at mating and particular reproduction traits were selection strategy dependent, such that identification of relationships between growth and reproduction traits will require measurement of additional growth traits at an earlier age than in the current study

Influence of the correlation between growth rate and backfat on selection response in pigs

1990 ◽  
Vol 1990 ◽  
pp. 84-84
Author(s):  
P. R. Bampton ◽  
A. J. Webb
Keyword(s):  
Growth Rate ◽  
Performance Test ◽  
Performance Testing ◽  
Selection Response ◽  
Economic Traits ◽  
Lean Growth ◽  
Genetic And Phenotypic Correlations ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

Backfat levels in pigs have declined rapidly in the last decade and are approaching an economic optimum. As optimal levels of backfat are achieved this has two important implications for selection objectives. First, the relative emphasis of selection will shift to other traits, particularly lean growth rate. Second, there will also be a move towards ad libitum feeding on performance test to allow expression of appetite and to increase response to selection for lean growth rate. The effect of very lean pigs coupled with ad libitum feeding may result in changes in the genetic and phenotypic relationship between growth rate and fat depths. Reported genetic and phenotypic correlations between growth rate and backfat range from +0.3 on ad libitum feeding to -0.3 on restricted feeding. In most performance testing regimes the key relationship is between growth rate and ultrasonic fat depths which in contrast to other economic traits are often unfavourably correlated.

Genetics of food intake in the pig

1989 ◽  
Vol 13 ◽  
pp. 41-50 ◽  
Author(s):  
A. J. Webb
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Genetic Correlations ◽  
Live Weight ◽  
Selection Strategy ◽  
Selection Regime ◽  
Lean Growth ◽  
Optimum Selection ◽  
Ad Libitum ◽  
Selection For

AbstractThe rôle of voluntary food intake, measured as daily food consumption on ad libitum feeding from 30 to 90 kg live weight, in future selection strategy is reviewed. Intake shows a heritability of 0.3, and genetic correlations of 0.6 with growth rate and –0.4 with leanness. Low genetic correlations between test station and commercial farm performance are reported for growth rate (0.27) and backfat (0.41) which arise either from genotype × feeding level interactions, or from individual feeding at stations. Selection for rate of lean growth appears to lead to a primary increase in rate of protein deposition, whereas selection for efficiency of lean growth appears to lead to a reduction in rate of fat deposition via a decline in intake. Continued reduction in intake may limit further improvement in lean growth rate and sow productivity. As optimum fatness is approached, the selection emphasis is expected to swing towards rate of lean growth to reduce total food used for maintenance. To determine the optimum selection regime, a knowledge is required of the genetic relationship between intake and lean growth rate. Meanwhile, the optimum selection regime may involve ad libitum group feeding with electronic recording of individual food intake. In the long term, exogenous or endogenous growth promoters could remove the need for selection against backfat, and necessitate a radical genetic increase in intake.

scholarly journals Responses to selection for lean growth in sheep

2002 ◽  
Vol 74 (1) ◽  
pp. 39-50 ◽  
Author(s):  
G. Simm ◽  
R.M. Lewis ◽  
B. Grundy ◽  
W.S. Dingwall
Keyword(s):  
Fixed Effects ◽  
Mixed Model ◽  
Live Weight ◽  
Control Line ◽  
Breeding Values ◽  
Breeding Goal ◽  
Lean Growth ◽  
Selection For ◽  
Estimated Breeding Values ◽  
And Control

AbstractThis paper reports the selection responses achieved, and related results, following 9 years of index selection for lean growth in Suffolk sheep. The breeding goal of the index used comprised carcass lean weight and carcass fat weight at a constant age, with relative economic values of + 3 and –1 per kg. The selection criteria were live weight (LWT), ultrasonic fat depth (UFD) and ultrasonic muscle depth (UMD) adjusted to a constant age of 150 days. By year 9, responses in LWT, UFD and UMD in both sexes, as judged by the divergence between selection and control line performance, amounted to 4·88 kg, -1·1 mm and 2·8 mm respectively; these responses are between 7 and 15% of the overall means of the traits concerned. Although selection was originally on index scores based on phenotypic records, the retrospective analyses reported here used the mixed model applications of residual maximum likelihood to estimate parameters and best linear unbiased prediction to predict breeding values. The statistical model comprised fixed effects plus random effects accounting for direct additive, maternal additive and temporary environmental variation. Estimated genetic trends obtained by regressing estimated breeding values on year of birth were similar to annual responses estimated by comparing selection and control line means. Estimates of direct heritabilities were 0·054, 0·177, 0·286, 0·561 and 0·410 for birth weight (BWT), weaning weight (WWT), LWT, UFD and UMD respectively. Corresponding estimates of maternal heritabilities were 0·287, 0·205, 0·160, 0·083 and 0·164. Phenotypic correlations between all pairs of traits were positive and usually moderately high. There were low negative direct additive correlations between BWT and WWT, and between BWT and LWT, but higher positive maternal additive correlations between all other pairs of weight traits.

Selection for lean growth rate and correlated responses in litter traits in a synthetic line of Yorkshire-Meishan pigs

2001 ◽  
Vol 81 (2) ◽  
pp. 205-214 ◽  
Author(s):  
P. Chen ◽  
T. J. Baas ◽  
J. C. M. Dekkers ◽  
L. L. Christian
Keyword(s):  
Growth Rate ◽  
Regression Coefficients ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Correlated Responses ◽  
Lean Growth ◽  
Litter Traits ◽  
Selection For ◽  
Synthetic Line

Selection for lean growth rate (LGR) was conducted for four generations in a synthetic line of Yorkshire-Meishan pigs to study the effectiveness of selection for LGR and correlated responses in litter traits. Lean growth rate was estimated from ultrasound measurements of 10th-rib backfat thickness and longissimus muscle area. In the selection line, 7 boars and 20 gilts with the highest LGR were selected to produce the next generation. The generation interval was 13 mo and the average selection differential per generation was 1.1 phenotypic standard deviation units. A contemporaneous control line was maintained by randomly selecting 5 boars and 15 gilts. Data from a total of 1057 pigs sired by 58 boars and out of 133 sows were available from the two lines. Selection responses were estimated from deviations of the selection line from the control line using least squares (LS) and by multiple trait derivative-free restricted maximum likelihood analysis using an animal model (AM). The estimate of response to selection per generation using LS was 9.4 ± 0.95 g d–1 for LGR. The corresponding estimate from the AM was 9.8 ± 0.51 g d–1. Correlated responses in litter traits were regressed on generation. For the LS method, regression coefficients were negative but not significant (P > 0.05) for total number born, number born alive, and number at 21 d and at 42 d. Significant, positive correlated responses occurred in 42-d litter weight and 21-d piglet weight (P < 0.05). For the AM method, the regression coefficients were also negative, but were not significant (P > 0.05) for numberalive at birth, at 21 d, and at 42 d. A significant positive correlated response occurred only for 42-d litter weight (P < 0.05). Although results are based on a population of limited size, it can be concluded that selection for LGR in a synthetic line is effective and should have little effect on litter traits. Key words: Pigs, selection, lean growth rate, correlated response

Selection for components of efficient lean growth in Landrace pigs

1994 ◽  
Vol 1994 ◽  
pp. 10-10
Author(s):  
M.K. Curran ◽  
N.D. Cameron
Keyword(s):  
Growth Rate ◽  
Selection Criteria ◽  
Conversion Ratio ◽  
Control Line ◽  
Food Conversion ◽  
Lean Growth ◽  
Food Conversion Ratio ◽  
Daily Food ◽  
Selection For ◽  
One Year

To study responses to divergent selection for lean growth rate (LGA), lean food conversion ratio (LFC) and daily food intake (DFI), an experiment was started in 1984 at Edinburgh and Wye. This paper measured the selection pressure applied, the responses in the selection criteria and estimated the genetic and phenotypic relationships between the selection criteria with ad-libitum feeding of Landrace pigs after four generations of selection.The LGA (LFC) selection objective was to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The LGA, LFC and DFI selection criteria had phenotypic s.d. of 32, 29 and 270 units and results are presented in s.d. units.Boars and gilts were purchased from eight British nucleus herds and boars from national artificial insemination centres in 1982. Homozygous or heterozygous halothane positive pigs were not included in the experiment. The base population consisted of 20 sires and 89 dams. Within each of the three selection groups, there were high and low selection lines with a control line, each consisting of 10 boars and 20 gilts, with a generation interval of one year. There were two control lines, one for LGA and one for LFC and DFI, as selection groups were arrowed continuously. The total number of pigs tested per line and average inbreeding coefficient at generation 4, within selection group are given below.

Sign in / Sign up

Export Citation Format

Share Document